In this photo released by the Syrian official news agency SANA, pro-government Syrian protesters hold portraits of Syrian President Bashar Assad as they march during a demonstration at Kafar Souseh neighborhood in Damascus, Syria, Friday, Feb. 7, 2014. The Syrian government announced it will take part in a second round of peace talks in Geneva on Monday. The first face-to-face U.N.-hosted talks adjourned on Jan. 31. (AP Photo/SANA)

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In this video image released by the Syrian official news agency SANA, Syrian citizens sit aboard a bus after they evacuated the besieged rebel-held neighborhood of of Jouret el-Shayah, in Homs province, Syria, Friday, Feb. 7, 2014. The Syrian government on Friday began evacuating civilians trapped in rebel-held parts of a battleground city under a rare deal struck between the government and the opposition that also included a three-day cease-fire allowing humanitarian aid convoys to the besieged areas. (AP Photo/SANA)

BEIRUT — Renewed fighting broke a cease-fire in the embattled central Syrian city of Homs and halted a plan to evacuate civilians and bring supplies into rebel-held areas under siege, an official and activists said Saturday.

The official said the fighting included a mortar that landed near U.N. personnel. An activist said combat began when government forces fired 11 rockets toward the rebel-held Hamidiyeh quarter. The official spoke on condition of anonymity because he was not authorized to brief reporters.

The mortar did not cause any injury to U.N. officials. The U.N. had no immediate comment.

Syrian forces loyal President Bashar Assad have prevented the entry of food and medical aid into rebel-held parts of the city for over a year, badly affecting hundreds of civilians holed up in the areas. An agreement had called for a three-day truce to allow the evacuation of some civilians and the entry of food shipments.

The agreement was reached after talks last month in Switzerland between government officials and opposition activists in exile to try to end Syria’s three-year conflict. The parties are expected to meet again on Feb. 10.

On Friday, 83 children, women and elderly people on wheelchairs were evacuated from Homs, the U.N. said.

The city was one of the first areas to rise up against Assad in 2011 and has been particularly hard hit by the war. Over the past year, the government has regained control over much of Homs, except for a few neighborhoods in the historic center.

On Saturday, a coalition of exiled Syrian activists said they feared the agreement would be used as a “prelude to the regime destroying the city.”

“It has used similar deals to buy time to strengthen its positions on the ground and to kill more civilians,” said the Syrian Coalition in a statement issued Saturday.

Also Saturday, military aircraft dropped barrels bombs on rebel-held areas in the northern city of Aleppo, killing at least 15. The bombings are part of a weekslong campaign by Assad’s forces to wrest control of the city, parts of which were seized by rebels in mid-2012.

Activists say the massive barrel bombs often prepare the way for a government advance. But the crude weapons — cylinders packed with explosives and shrapnel dropped usually from helicopters — cannot be aimed precisely and have killed hundreds of civilians.

More than five such bombs exploded on roads in the adjacent areas of Masaken Hanano and Haidariyeh, said Mohammed Wissam of the Aleppo Media Center. Other bombs fell on the Kalaseh district, the Aleppo Media Center reported. The activist collective, the Local Coordination Committees, also reported the bombings.

Wissam said four people were killed in Masaken Hanano and another 11 were killed in Haidariyeh.

Video footage of one incident started with a thundering explosion followed by a column of smoke billowing to the sky. Men rushed about a damaged building, pulling out smashed bodies. They carried them on makeshift stretchers of cardboard and blankets, laying the dead on a sidewalk. One man placed a severed limb next to a sprawled body. Men rushed to an ambulance carrying a white sheet laden with body parts; they said they had collected four bodies.

The videos could not be independently authenticated but appeared genuine and corresponded with Associated Press reporting of the event.

Thousands of civilians have fled other pummeled rebel-held areas, said activist Wissam. Their numbers add to the millions who have been displaced during Syria’s three-year uprising that began as largely peaceful demonstrations in March 2011.

Also Saturday, the Britain-based Syrian Observatory for Human Rights said they had counted 16 people killed, including five children and a woman, in a government-controlled part of Aleppo. The incidence occurred on Friday, said the Observatory, which relies on a network of activists on the ground.